CN1376808A

CN1376808A - Stainless ferrite steel containing rare earth

Info

Publication number: CN1376808A
Application number: CN 01138314
Authority: CN
Inventors: 束润涛
Original assignee: Individual
Current assignee: Individual
Priority date: 2001-12-18
Filing date: 2001-12-18
Publication date: 2002-10-30

Abstract

A stainless ferrite steel containing rare-earth elements features that it has high weld performance and purity as it contains rare-earth elements, and Ti or Nb. Said steel (ocr13Ti(or Nb)RE) tube can be used to make tube bank of heat exchanger and its plate can be used to make the structural member in tower and tower trays. Its advantages are no stress corrosion, high anticorrosion power and low cost.

Description

A kind of ferritic stainless steel that adds rare earth

The present invention relates to corrosion-resistant pipe shell heat exchanger, condenser and air cooler weldless steel tube and the tower inner member and the tower tray of industries such as oil, chemical industry, electric power.

At oil, chemical industry, in the industries such as electric power, exist in the environment of a large amount of chlorions and hydrogen sulfide corrosion, tube and shell heat exchanger, condenser and finned air cooler, because the thin (δ≤3.5mm) of heat transfer tube and finned tube parent tube wall thickness, the plain carbon stool pipe is (as No. 10, No. 20) do not possess corrosion resistance, generally can only be with just corrosion failure of some months, though and austenitic stainless steel has anti-preferably pitting corrosion, spot corrosion and uniform corrosion performance, but because austenitic stainless steel (18-8,304L, 316,316L) anticorrosion stress-resistant performance extreme difference and limited it and in chloride ion-containing and hydrogen sulfide medium environment, used.HCl-H as normal top condenser in the oil refining apparatus ₂In the S corrosive medium, some enterprises have selected for use expensive duplex stainless steel or titanium pipe to do heat exchanger tube, but are difficult to generally be applied owing to it costs an arm and a leg.For a long time in similar corrosive environment, be difficult to find a kind of alternative material of economy and durability always, many enterprises have to be dealt with the form of spraying, but the work-ing life of carbon steel spraying can be above 2 years yet, come off easily because carbon steel is sprayed under the effect of high temperature and flow velocity, still be difficult to satisfy the requirement of production equipment long-term operation.The 0Cr13 steel of former national standard, its chemical composition design are to formulate the seventies and use till today, and the composition of Si and Mn is higher, have certain fragility harm, and the control that the bigger Cu of ferrite harm and Ni are not also carried out minimum requirements.Though there is sheet material using, 0Cr13 can produce very tangible brittle crack during according to old standard colddrawing seamless pipe.In addition, owing to do not have stabilizing element Ti or Nb in the composition design, material Cr when welding separates out from the heat affected zone, can cause the poor Cr of weld metal zone, therefore, easily causes intergranular corrosion harm, and then easily produces stress corrosion inclination.

The objective of the invention is provides a kind of both anti-muriate and H 2 S stress corrosion for industries such as oil, chemical industry, electric power, the ferrite stainless steel tubing and the thin plate that add rare earth that certain anti-uniform corrosion ability is arranged again, and, make tower inner member and tower tray with the ferrite stainless steel material that adds rare earth with the ferrite stainless steel tubing manufacturing interchanger and the air cooler that add rare earth.

The objective of the invention is by following scheme implementation:

Develop a kind of both anti-muriate and H 2 S stress corrosion, the high alloy ferrite stainless steel material that adds rare earth of anti-again certain uniform corrosion ability has good welding property simultaneously again.Key is to add rare earth (RE), Ti or Nb in alloying constituent, (%) is as follows for its chemical ingredients:

C≤0.06; Si≤0.50; Mn≤0.50; Cr:11.0-15.0; Ni≤0.25; Cu≤0.25; Ti (or Nb): 5 * C≤0.80; S≤0.025; P≤0.030; RE add-on≤0.20; Surplus is iron (Fe).

(%) is as follows for the embodiment chemical ingredients:

C≤0.06; Si≤0.50; Mn≤0.50; Cr:12.0-14.0; Ni≤0.20; Cu≤0.20; Ti:5 * C≤0.80; S≤0.015; P≤0.030; RE add-on≤0.20; Surplus is iron (Fe).Determine that according to the proportioning of chemical ingredients in the steel its grade of steel is 0Cr13Ti (or Nb) RE.

A. since in the steel content of austenite former Ni extremely low, so 0Cr13Ti (or Nb) RE belongs to pure ferritic stainless steel, when Cu+Ni in the steel≤0.50%, the 0Cr13Ti of annealed state (or Nb) RE does not produce the chloride stress cracking corrosion failure.

B. in order to prevent intergranular corrosion, stabilizing element Ti (or Nb) must satisfy: 5 * C and≤0.80%.Xiang Gangzhong adds Ti (or Nb), can make the carbide, the nitride that contain chromium in the steel transfer to form titaniferous carbide, nitride, and carbon and nitrogen are played static stabilization, and the crystal grain of refinement ferritic stainless steel.The effect of metal niobium Nb and metal Ti is the same, and C is played static stabilization.

C. add rare earth (RE) and be the outstanding feature of the technical program in composition design, the adding of rare earth is to control form, size and the quantity of steel inclusion, does not up to the present domesticly also add the precedent that rare earth carries out industrial application in stainless steel.Because rare earth (RE) can have great affinity interaction with low melting point metal and nonmetal composition S, O, N, C, the Si in the steel, can control the form and the size of the inclusion in the steel effectively, pure steel, the corrosion resistance and the impelling strength of raising steel.Simultaneously, because C, N in rare earth energy and the steel form corresponding compounds, when welding, can stop heat affected zone Cr effectively ₂₃C ₆And Cr ₂N separates out at crystal boundary, is quite useful to the intergranular corrosion resistance ability that improves ferritic stainless steel.The ability of rare earth desulfurization and deoxidation and calcium magnesium seemingly and can be controlled form, size and the quantity of the inclusion of oxygen and sulphur in the steel effectively, and the optimum ratio relation of rare earth and sulphur (RE/S) residual component in steel should be controlled in 2 to 6.

D. 0Cr13Ti (or Nb) RE steel can be smelted with electric furnace, open hearth or external refining.Weldless steel tube adopts the method manufacturing of cold-drawn.0Cr13Ti (or Nb) RE steel all adopts annealing to heat-treat.

With the steel billet of 0Cr13Ti (or Nb) RE can rolling≤5mm thin plate, weldless steel tube that also can rolling wall thickness≤5mm.

The tube bank that can make interchanger and condenser with 0Cr13Ti (or Nb) RE weldless steel tube material; Can make tower inner member and tower tray with 0Cr13Ti (or Nb) RE steel board.Produce too much carbide Cr at weld heat-affected zone when preventing the welding of this material ₂₃C ₆And Cr ₂N, the welding material of 0Cr13Ti (or Nb) RE should be used Ultralow Carbon Stainless Steel welding wire 308L (H00Cr20Ni10) or H00Cr18Ni12Mo2; With the argon arc welding welding, without preheating and thermal treatment, weld seam is ferrite and austenite duplex structure, and there is not the chloride stress cracking corrosion tendency in two-phase steel organization, still has goodish corrosion resistance nature.

A kind of ferritic stainless steel that adds rare earth of the present invention has excellent corrosion resisting performance, is a kind of inexpensive steel grade.That 0Cr13Ti (or Nb) RE steel pipe and equipment can be used for refining oil is normal, chlorion (100-140 ℃) corrosion of decompression overhead condenser, and interchanger at the bottom of high temperature resistance sulphur (〉=240 ℃) the corrosive tower in the oil refining apparatus.Tower inner member and tower tray that 0Cr13Ti (or Nb) RE sheet material is manufactured can be used for cat head HCl-H ₂S-H ₂O, HCN-H ₂S-H ₂The low temperature corrosion environment of O, and high-temperature sulfur corrosion environment.Compare with the 18-8 austenitic stainless steel, owing to there is not the alloying element of counter stress corrosion-susceptible in the composition design, the counter stress corrosion has the geneogenous ability of exempting from service, thereby has goodish anticorrosion stress-resistant performance.Because the adding of Ti has improved material welding performance greatly; The adding of RE then greatly reduces the foreign matter content of S in the steel, and the inclusion in the steel has been played effective control.The equipment total cost of 0Cr13Ti (or Nb) RE tubing and sheet material manufacturing is lower than the 18-8 austenitic stainless steel, and can overcome the insoluble stress corrosion harm of 18-8 austenitic stainless steel institute, has boundless market outlook.The interchanger and the air cooler that can be widely used in the relevant corrosive environment of industries such as oil, chemical industry, electric power.

Claims

1. ferritic stainless steel that adds rare earth, it is made of alloying elements such as C, Si, Mn, S, P and Cr, Mo, Ti, and it is characterized in that: the chemical ingredients of adding rare earth (RE) in alloying constituent is as follows: C≤0.06%; Si≤0.50%; Mn≤0.50%; Cr:11.0-15.0%; Ni≤0.25%; Cu≤0.25%; Ti (or Nb): 5 * C≤0.80%; S≤0.025; P≤0.030; RE add-on≤0.20; Surplus is iron (Fe).

2. as claims 1 described ferritic stainless steel that adds rare earth, it is characterized in that: with the steel billet of the described ferrite stainless steel chemical composition that adds rare earth can rolling≤5mm thin plate, weldless steel tube that also can rolling wall thickness≤5mm.

3. as claims 1 described ferritic stainless steel that adds rare earth, it is characterized in that:, make tower inner member and tower tray with the thin plate of described ferrite stainless steel chemical composition with the tube bank that the weldless steel tube of described ferrite stainless steel chemical composition can be made interchanger.